I have recently taken part in some altitude training in Kenya and boy was it hard work! Trainers in endurance events exercise a training technique known as altitude training. Several decades back, scientists found that individuals who reside in the hills, where the atmosphere contains lower amounts of oxygen, have higher than normal blood glucose amounts. This means that many athletes travel to high altitude areas in Africa for this type of training. A limiting factor in events that require endurance is that the time necessary to transfer oxygen from the lungs to the muscles. Since more than 98 percent of the oxygen from the blood is bound to red blood cells, individuals who have high numbers of red blood cells ought to consume high amounts of oxygen and so consume more oxygen available due to their own muscles, giving them higher endurance. It looks like altitude training at high elevation would enhance performance much more, so theoretically, all long distance runners, cross country skiers, bike racers along with additional athletes in endurance sports benefit from training and living in high altitudes.
But you can not train as deeply from the hills where oxygen is lean. Deficiency of oxygen through hard exercise slows down you. 1 set of investigators decided to determine if residing at high altitudes would raise red blood glucose focus, and training in low elevation would enable the athletes to carry out tougher workouts. The athletes that did this had a greater maximal oxygen uptakes, greater maximal aerobic power and reduced resting heart rates compared to the control group. The blood of those altitude trained athletes can carry more oxygen, and the oxygen concentration in their blood would go back to normal earlier after extreme contests so their performance was massively improved.